Abstract: To investigate the effect of the amount and position of the heated compartments on fire behaviour of continuous slabs, this paper conducted fire tests on three continuous slabs. One has fire exerted at the side span only, one has fire exerted at both the side and the mid spans, and the other has fire exerted at all the three spans. The furnace temperatures of each span, the temperature of concrete and steel, the slab deflection, the restraint forces at slab corners and failure modes were obtained. Adopting the plastic damage model on the ABAQUS platform, the numerical analyses were conducted to predict the temperature, the deflection and the mechanical mechanism of tested slabs. The comparison between the test results and numerical results were also conducted, showing that the amount and position of the heated spans have significant effects on the cracking pattern, the deflection and the failure mode of continuous slabs. The short vertical slab cracks appear on the bottom surface of the heated spans, the cracks paralleled to the short-span appear on the top surface of the heated spans and the cracks are adjacent to interior supports. The mid-span vertical deflection of the side span gradually increases with the increase of temperature, and the increase of the deflection of mid span mainly depends on the heated effect of its adjacent spans. In addition, numerical results show that the moment mechanisms of the heated span during the heating stage is different with that during cooling stage. The moments near the internal supports are larger than those at other places. The axial forces in the continuous slab are compressive, and the maximum equivalent plastic tensile strains mainly concentrate near the internal supports (top surface) and the outer sides (bottom surface).